The present invention relates in general to brake systems of motor vehicles and has specific reference to a servo-controlled brake device intended for making up any failure in the normal servo control means by implementing safety brake means, the device according to this invention being particularly simple and efficient, and becoming operative automatically in case of failure of the normal servo control means as the driver continues to depress the brake pedal normally.
Basically and for this purpose the safety brake device according to this invention for a servo-controlled brake system of motor vehicles of the type having a source of fluid under pressure, is characterized in that it comprises a member which is adapted to transmit the braking effort exerted by the driver and which is associated with the normal foot-operated control member, such as the conventional brake pedal, and operatively connected to the normal control member through locking means such that the locking means is maintained in a locking position by the fluid under pressure from the source and released in case of pressure drop or failure to permit an extra stroke of the normal control member which is utilized for operating safety brake means.
The manner in which this locking action may be provided through simple hydraulic or hydromechanical means will be explained presently in detail, the safety brake means being notably of the hydraulic or mechanical type.